The Ukrainian General Staff wrote on its Facebook page that the plane went down Saturday during a routine flight. An investigation into the crash is underway.
Su-27 fighter jets were designed by the Soviet Union and continue to be built by Russia. Depending on the model, they carry either one or two pilots. It was not immediately clear what the model was in Saturday's crash.
Ukraine lost a two-seat Su-27 in October during exercises with the U.S. Air National Guard. An American pilot, riding in the second seat, died along with his Ukrainian comrade.
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